Email troubleshooting guides
MX and DNS routing, organized by problem
Diagnose missing, conflicting, changed, or intentionally disabled mail routing.
Choose the article that matches the provider, record type, or exact error shown in your mail logs.
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Email delivery delayed or rejected after a DNS migrationDiagnose email that stopped arriving after a DNS change. Compare public MX records with the intended provider and avoid false alarms for mail gateways.
Null MX conflicts with ordinary MX recordsDiagnose Null MX email rejection. Learn when MX 0 . is valid, find conflicting ordinary MX records, and repair incoming mail routing safely.
Primary sources: Primary technical reference.